HSNF5 Is Required for Human Papillomavirus E2-Driven Transcriptional Activation and DNA Replication

Abstract

Objective: To determine the participation of the SWI/SNF complex in the transcription and replication of human papillomavirus (HPV) E2 protein. Method: We checked the interaction between hSNF5 and HPV E2 through glutathione S-transferase (GST) pull-down and coimmunoprecipitation assays. The transcriptional activation of E2 was analyzed by reporter assay and the level of HPV DNA replication was determined by a transient DNA replication assay. Results: We demonstrated that hSNF5 binds to the HPV E2 protein in vivo and in vitro and activates E2-dependent viral transcription. SWI/SNF components enhanced E2-dependent viral transcription. The ATPase activity of BRG-1/hSNF2 was required for efficient E2-dependent transcriptional activation. Transient DNA replication assays showed that hSNF5 and BRG-1 enhance HPV-18 DNA replication in vivo. A dominant negative hSNF5 and a BRG-1 ATPase mutant each repressed E2-dependent viral transcription and E2-driven HPV DNA replication in vivo. The fact that the transcriptional activation function of HPV-18 E2 was defective in the SNF5 knockout strains of the yeast Saccharomyces cerevisiae implies that the SWI/SNF complex is required for the transcriptional activation function of E2. Conclusion: These results suggest that the SWI/SNF complex is involved in HPV E2-driven transcription and DNA replication via interaction with E2.